In 1634 Governor John Winthrop first fortified Castle Island, making it the earliest fortified site surviving on Boston Harbor. Commanding a view over the entrance to the harbor, the site was constantly renamed and rebuilt to fill the needs of the colony, commonwealth and nation. In 1798, Massachusetts sold the island to the federal government and President John Adams renamed it Fort Independence. French engineer John Foncin designed a new fort for the site, which was completed in 1809. Having fallen into disrepair, the fort was reconstructed on Foncin's plan between 1835 and 1851. With earthen revetments atop its one-tiered pentagon-plan ramparts, the brick and granite fort remained garrisoned through the Spanish-American War. As part of the development of South Boston and the municipal park system, first a bridge and then a causeway to the fort were constructed after 1891. Today one wonders at the term “Castle Island,” since the fort crowns the end of the South Boston landmass, standing powerfully at the entrance to the harbor channel.